1. Field of the Invention
This invention relates to methods and mechanisms for caching data in a blade server complex to reduce the likelihood that data will be unnecessarily cached.
2. Description of Background
“Blade” systems have gained widespread prominence and acceptance in server environments. A conventional Blade system may consist of one or more Processor Blades, and/or one or more Storage Blades. Conventional Processor Blades may not include high-capacity disk-type storage. Instead, conventional Processor Blades rely on Storage Blades to provide high-capacity storage. Both Processor Blades and Storage Blades include memory that is used to store “pages” of data that may contain information that may be accessed by a user of the Blade system. This memory is conventionally referred to as cache memory on the Storage Blade and main memory on the Processor Blade. Conventionally, as pages are loaded from disc storage on a Storage Blade, the pages are stored in cache memory. The Processor Blade may then access the page in the cache memory and move it to main memory, from which it may then be accessed by users of the Blade system.
In a Blade complex that includes at least one Processor Blade and at least one Storage Blade, pages are often cached in both the Processor Blade memory and the Storage Blade cache. This page duplication in both the processor memory and storage cache memory is unnecessary and inefficient. Often, pages cached in the Storage Blade cache memory will not be used again and pages not cached in the Storage Blade will be accessed soon by the Processor Blade. If the Storage Blade relies only on its own cache memory staging/destaging algorithm, it may stage pages that will not likely be accessed, and destage pages that will likely be re-accessed.
By caching pages in Storage Blade cache memory that may not be accessed, cache memory is used unnecessarily. Because the cache memory is forced to stage and destage pages that may not have needed to be cached in the first place, system latency is increased. Furthermore, staging and destaging of pages requires power. Accordingly, each staging or destaging both uses electricity and generates heat. Additionally, storage of pages in cache requires power. Because many unnecessary pages are stored in cache in conventional Storage Blades, system power usage is increased.
Accordingly, a need exists in the art for a system and method that is capable of reducing duplication of data caching in Blade systems.